Improving the quality of life, including environment and health, is one of the greatest challenges facing mankind in the 21 century. In view of this, high-preference products which provide an environment capable of enhancing the quality of healthy life for people and is required for a comfortable and easy life should be developed. Namely, human physical and emotional responses which change according to the surrounding environmental conditions need to be measured for application to the development of products.
For this purpose, emotional engineering studies focused on determining the relationship between products and the emotional and physiological state of people by observing the emotional and physiological responses of people to the products are currently being actively conducted in Korea and other countries. Such emotion-related studies have been conducted mainly on the sight and hearing senses, but are still insufficient on the sense of smell (fragrance).
The sense of smell is a chemical sense, unlike other senses (sight and hearing senses), and thus is difficult to study, because precise stimulus control is required and, in addition, nerve transmission to the brain simultaneously with the presentation of smell stimulus, the evaluation of mental emotion, and physiological changes (central and autonomic nervous systems) occur.
People frequently experience odors, stimulating the sense of smell, in their daily life, and the emotion of people is influenced by a variety of odors, including fragrant odors and unpleasant odors. Recently, studies on the effects of the odors of plants (such as garlic) and offensive odors (such as ammonia) on physiological action in addition to studies either on the effects of green shower or on the effects of pheromones on the sexual behavior of animals have been conducted.
The impulse of smell is transmitted to the limbic system through nasal olfactory cells to add the emotional factors of the olfactory sense, thus inducing emotional and physiological changes, such as pleasure, sickening, awakening or sleepy feelings. This phenomenon explains that when a person sniffs perfume, a strong mood is created, and when a person smells an unpleasant odor, defensive reflexes such as sneezing occur, and when a person smells an odor such as ammonia, the breath is temporarily stopped. As described above, the sense of smell plays a great role in the maintenance of human life and the discrimination of odors.
Sleep is an important physiological function in animals with developed brains and is an essential behavior for survival. All organisms on the earth live in an environment in which day and night alternate. Being synchronized to the diurnal cycle and repeating the rhythm of activity and rest according to this diurnal cycle are the most fundamental survival strategy of organisms. Therefore, all organisms have circadian biological clocks in the body and are entrained to the environmental cycle.
Lack of sleep causes a sleepy feeling or temper or reduces vital energy, leading to the loss of the quality of life. In some cases, it may cause seriously impair life quality. Sleep is a function for preventing such states from occurring, and for this reason, it is very important to sleep well.